“I had no idea!”
Hearing aids are not waterproof. Apparently, some make claims to being water resistant.
Unfortunately, you still cannot swim in a hearing aid. You cannot step into the shower with a hearing aid. If it rains on you, you must hide your hearing aid. You cannot even sweat too much while wearing a hearing aid. The water wrecks the electronics.
Siemens won honors in Design and Engineering at CES for creating a hearing aid that is totally waterproof. You can swim in the device and do any water activity without fear of wrecking the electronics.
As an added feature, they have an attachment that allows you to listen to any mp3 music player.